Precipitation process of the Ni3Al phase in copper-based alloys

• Autorzy: Stobrawa J. P. , Rdzawski Z. M.
• Języki publikacji: EN

Abstrakty

EN

Purpose: This research was aimed to investigate the mechanism of Ni3Al phase precipitation during long-term process of ageing Cu-Ni-Al type alloys with particular account of the precipitates morphology changes, including the changes in their size with varying temperature and ageing time, so as to determine an effect of the elastic strain energy on these changes. Design/methodology/approach: Samples of cold-rolled strips from the CuNi16Al5 alloy were solution – treated at 900°C for 1h in argon atmosphere, water quenched and next aged at the temperatures of 450 and 550°C for up to 380 and 760 hours, respectively. Their microstructure was investigated by transmission electron microscopy. Findings: It was found that decomposition of supersaturated solid solution proceeds by nucleation and growth of the coherent precipitates of the L12 – Ni3Al phase. Their morphology changes as a result of competitive influence of an elastic strain energy, surface energy on the matrix-precipitate inter-phase boundary, and the energy of elastic interaction between precipitates. The L12 – Ni3Al precipitates nucleate as the spherical ones and grow, forming intermediate sub-structures, until they reach a cubic form with the planes parallel to the {100} planes of a matrix and take privileged positions along the <110> directions. Clear deviations from the LSW coagulation theory and its modifications, demonstrated by the slow-down of the process, have been observed. In the extreme case, growth of the precipitates can be completely stopped in some time ranges of the ageing process. Research limitations/implications: Further research should be concentrated on the precipitation kinetics within a wider range of volumetric fraction of the Ni3Al phase in a copper matrix. Practical implications: This effect can be used in practice to stabilise mechanical properties at elevated temperature. Originality/value: The paper contributes to better understanding of the precipitation mechanism in the alloys examined.

Słowa kluczowe

EN

metallic alloys; electron microscopy; precipitation hardening; morphology

PL

stopy metali; mikroskopia elektronowa; utwardzanie wydzieleniowe; morfologia

• Wydawca: International OCSCO World Press
• Czasopismo: Journal of Achievements in Materials and Manufacturing Engineering
• Rocznik: 2006
• Tom: Vol. 15, nr 1-2
• Strony: 21--26
• Opis fizyczny: Bibliogr. 16 poz., rys., wykr.

Twórcy

autor

Stobrawa J. P.

• Division of Materials Processing Technology and Computer Techniques in Materials Science, Institute of Engineering Materials and Biomaterials, Silesian University of Technology, ul. Konarskiego 18a, 44-100 Gliwice, Poland
• Non-Ferrous Metals Institute, ul. Sowińskiego 5, 44-100 Gliwice, Poland

autor

Rdzawski Z. M.

• Division of Materials Processing Technology and Computer Techniques in Materials Science, Institute of Engineering Materials and Biomaterials, Silesian University of Technology, ul. Konarskiego 18a, 44-100 Gliwice, Poland
• Non-Ferrous Metals Institute, ul. Sowińskiego 5, 44-100 Gliwice, Poland

Bibliografia

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